Clustering of EEG Occipital Signals using K-means Víctor Asanza, Kerly Ochoa, Christian Sacarelo, Carlos Salazar, Francis Loayza, Carmen Vaca and Enrique Peláez Escuela Superior Politécnica del Litoral, ESPOL Facultad de Ingeniería en Electricidad y Computación Centro de Tecnología de información
INTRODUCTION:
Kadoya, K., Lu, P., Nguyen, K., Lee-Kubli, C., Kumamaru, H., Yao, L., ... & Takashima, Y. (2016). Spinal cord reconstitution with homologous neural grafts enables robust corticospinal regeneration. Nature medicine.
INTRODUCTION:
Different recording methods used to control BMIs Astrand, E., Wardak, C., & Ben Hamed, S. (2014). Selective visual attention to drive cognitive brain–machine interfaces: from concepts to neurofeedback and rehabilitation applications. Frontiers in systems neuroscience, 8, 144.
INTRODUCTION:
Range: uV – 10mV
Typical electrophysiological methods. - Macroscopic electroencephalography (EEG). - Mesoscopic electrocorticography (ECoG). - Implantable electrodes
Obien, M. E. J., Deligkaris, K., Bullmann, T., Bakkum, D. J., & Frey, U. (2015). Revealing neuronal function through microelectrode array recordings.Frontiers in neuroscience, 8, 423.
INTRODUCTION:
Five typical arm spasticity patterns. Jost, W. H., Hefter, H., Reissig, A., Kollewe, K., & Wissel, J. (2014). Efficacy and safety of botulinum toxin type A (Dysport) for the treatment of post-stroke arm spasticity: Results of the German–Austrian open-label post-marketing surveillance prospective study. Journal of the neurological sciences, 337(1), 86-90.
INTRODUCTION:
Emotiv EEG electrode locations
www.emotiv.com
METHODOLOGY: EEG Signal Acquisition
EEG Signal Pre-Processing
EEG Signal Processing: Feature Selection & K-means Algorithm
METHODOLOGY: VOLUNTEERS Number of healthy volunteers:
5
Repeat an experiment :
10 times
EMOTIV EPOC Sampling Rate:
128 samples por second
Channels:
14
Resolution:
14 bits
VISUAL STIMULATION Frequency:
5, 6, 7, 8, 9, 24, 26, 27, 28, 29 Hz
Duration Time:
19,5 seconds Visual stimuli generated by a display with LEDs used to acquire the occipital EEG signals.
METHODOLOGY:
- 2500 Samples. - EEG Electrodes: Left Occipital (LO) and Right Occipital (RO).
Distribution of the 2 occipital electrodes Emotiv equipment.
METHODOLOGY: 2500 x 20 10 Frequencies LO 10 Frequencies 2500 x 20 10 Frequencies LO RO 2500 x 20 10 Frequencies LO RO 10 Frequencies 2500 x 20 10 Frequencies LO RO 10 Frequencies 2500 2500 x 20 1010 Frequencies LORO Frequencies Samples 2500 10 Frequencies RO 2500 Samples 2500 Samples 2500 Samples Samples
DC artifacts present in the occipital EEG signals 5Hz visual stimulus. f=: 5, 6, 7, 8, 9, 24, 26, 27, 28, 29 Hz
METHODOLOGY:
An analysis to the FFT frequency of the EEG signal.
METHODOLOGY:
- H0: EEG were not normal distributed with zero mean and variance value of 1. - H1: EEG were normal distributed with zero mean and variance value of 1.
a) Histogram of the EEG signal without pre-processing to occipital area with 5Hz visual stimulus. b) Comparison between the distribution of the EEG acquired data vs data from a normal distribution.
METHODOLOGY:
Butterworth filter 3er Orden (2-40)Hz
RESULTS :
EEG signal whithout DC artifacts in the 2 electrodes of the occipital area.
RESULTS :
Frequency analysis filtered with the FFT of the EEG signals.
RESULTS :
- H0: EEG were not normal distributed with zero mean and variance value of 1. - H1: EEG were normal distributed with zero mean and variance value of 1.
a) Histogram of the EEG signal with pre-processing to occipital area with 5Hz visual stimulus. b) Comparison between the distribution of the EEG acquired data vs data from a normal distribution.
RESULTS : Features Slection 100 x 30
100 (5 Volunteers x 10 Frequency x 2 Electrodes)
30 ([7 F. Time + 8 F. Frequency] x 2 electrodes)
FEATURES Variance (Time and Frequency):
Var(t,f)
Covariance (Time and Frequency):
Cov(t,f)
Correlation (Time and Frequency):
Corr(t,f)
Index Maximun Frequency: Minimum, Maximum, Median, Arithmetic average:
WhichMax(f) Time and Frequency
RESULTS :
Sum Squared Erros (SS) vs the number of k clusters
RESULTS :
EEG signals in the frequency range 5-9 Hz (cluster 1) and in the range of 24 to 29 Hz (cluster 2).
HIT RESULTS USING K-MEANS TO DIFFERENT GROUPS OF FEATURES.
CONCLUSIONS : - Normal distribution test on EEG. - Better cluster is obtaining by measuring the values of the index of maximum frequency. - One in the frequency range of 5 through 9 Hz (cluster 1) and another in the range of 24 to 29 Hz (cluster 2).
To learn more about this work:
- IEEExplore: http://ieeexplore.ieee.org/abstract/document/7750874/ - Mail vasanza:
[email protected] - Project: Semantic Interpretation of Brain Signals
